diff --git a/src/interceptors/ClientRequest/agents.ts b/src/interceptors/ClientRequest/agents.ts
index 5436f94c..e5f95a82 100644
--- a/src/interceptors/ClientRequest/agents.ts
+++ b/src/interceptors/ClientRequest/agents.ts
@@ -31,7 +31,7 @@ export class MockAgent extends http.Agent {
     this.onResponse = options.onResponse
   }
 
-  public createConnection(options: any, callback: any) {
+  public createConnection(options: any, callback: any): net.Socket {
     const createConnection =
       (this.customAgent instanceof http.Agent &&
         this.customAgent.createConnection) ||
@@ -64,7 +64,7 @@ export class MockHttpsAgent extends https.Agent {
     this.onResponse = options.onResponse
   }
 
-  public createConnection(options: any, callback: any) {
+  public createConnection(options: any, callback: any): net.Socket {
     const createConnection =
       (this.customAgent instanceof https.Agent &&
         this.customAgent.createConnection) ||
diff --git a/src/interceptors/XMLHttpRequest/utils/createEvent.ts b/src/interceptors/XMLHttpRequest/utils/createEvent.ts
index bc35ffd3..be87b369 100644
--- a/src/interceptors/XMLHttpRequest/utils/createEvent.ts
+++ b/src/interceptors/XMLHttpRequest/utils/createEvent.ts
@@ -7,7 +7,7 @@ export function createEvent(
   target: XMLHttpRequest | XMLHttpRequestUpload,
   type: string,
   init?: ProgressEventInit
-): EventPolyfill {
+): EventPolyfill | ProgressEvent {
   const progressEvents = [
     'error',
     'progress',